BACKGROUND: Late-life depression (LLD) represents a growing global public health concern. This study aimed to assess the worldwide burden of LLD using comprehensive data. METHODS: Leveraging the latest evidence from the Global Burden of Disease Study, we analyzed trends in LLD burden from 1990 to 2021, encompassing incidence, prevalence, and disability-adjusted life years (DALYs). We quantified disparities in LLD burden across socioeconomic, gender, regional, and national dimensions. Decomposition analysis was employed to identify key drivers of LLD burden variation. Frontier analysis illustrated the potential for burden reduction in various countries. RESULTS: Globally, there were 49,137,544 new cases, 46,672,175 prevalent cases, and 7,351,377 DALYs attributed to LLD in 2021. Between 1990 and 2021, the agestandardised incidence rate (ASIR), age-standardised prevalence rate (ASPR), and age-standardised DALYs rate (ASDR) of LLD all rose. In 2021, low SDI regions exhibited the highest all ASRs, while middle SDI regions had the fastest growth rates in these indicators. Regionally, Central and Eastern Sub-Saharan Africa had the highest ASIR, ASPR, and ASDR, respectively. Nationally, Uganda ranked highest in all ASRs in 2021. Women had higher burdens than men. Population growth was a primary driver of DALYs increase in middle SDI regions that had the greatest potential for improvement. CONCLUSIONS: The global burden of LLD has risen, with marked inequities across SDI, gender, region, and country. The burden is most pronounced in low and middle SDI regions. These findings offer guidance for developing LLD screening guidelines and enhancing prevention and intervention strategies in relevant countries, particularly Uganda.